A few recent XBLA playthroughs:
Fusion: Genesis - This is basically a semi-offline MMO twin-stick shooter space mining exploration combat game. It's very very ambitious, especially the MMO features; you're constantly online and people who go to the same map you're on automatically get matchmade with you so you can generally see other players flying around. If you take place in a big fleet-vs-fleet spaceship battle and another playing is aligned with the faction that's opposing you, then they'll show up fighting against you. There are 5 factions you can join; Cops, Thieves, Traders, or two warring factions (one is sort of a religious cult, one is sort of an Empire). Each faction has 4 types of ships each with 4 levels. Each faction has 9 unique faction missions + there are 9 unique main storyline missions + unlimited randomly generated grinding missions + Big army battles + 10+ tower defence type maps + one final dungeon raid against some pretty tough bosses. There's an auction house, and the game links up with a companion game for Windows Phone 7. The scope is really unheard of in a downloadable game. If there's a downside, it's that you need to do pretty significant amounts of busywork between unlocking actual unique missions... I'm not sure if this is typical of MMOs, since they're clearly aping the MMO formula, but it's something that frustrated me a little. Still, I'd say I got 15-20 hours out of it. I finished every mission, grinded to get the best weapons, leveled up to the level cap, and did a ton of raiding. One other quid pro quo--search out some FAQs. The UI is very unhelpful and there are basically no in-game tutorials so half the mechanics require outside reading to understand them. Once you do it's easy to do what you want and build the character you want, but in the mean time, it's obtuse. Again, I'm sure this is a result of them assuming their audience are MMO players. Very fun, highly recommend it the next time it's on sale if you like the demo. I got 200/200 achievements in it.
Puzzle Quest - Yeah, so, I've owned this for 5 years. I basically think it's a very compelling and addictive game, but not a good one. Virtually nothing that the game adds to the basic Bejeweled formula is all that enjoyable. The XBLA version has some significant balance fixes over the original release to prevent infinite combos. There doesn't seem to be much of a skill element. There's a lot of frustrating random elements, particularly in any of the side modes where getting a "no moves" gets you a game over. I had several occasions where I made a single move on those boards and then got a game over. I also find that pretty much every stat and game mechanic is not explained very well in-game.
My biggest problem is that you can be a level 40 badass at the end of the game with super high stats... and if you fight a Level 1 rat, it still takes 3-5+ minutes to beat. So basically the whole game feels like an endless slog. Even if you're super high level, it takes a few minutes in a match to build up your mana levels to the point that you can start really taking advantage of your skills and build, so pretty much every fight starts with the same tedious resource buildup. Start quest -> Identical fight to the last 200 fights you did -> 10 minutes later you win -> Get useless quest reward -> start next quest -> etc. Some of the plot stuff is vaguely interesting but the presentation is designed to be pretty minimal so it's a bit hard to get invested in any kind of characters or anything.
I felt like what I feel like when I get a craving for a bag of cheezies. I eat the first few and it's awesome and I keep going and at some point I realize that I hate them but I still keep going anyway and then the bag is finished and I'm miserable and frustrated, even though I know I did it to myself.
Unfortunately I can't get 200/200 since you need to win an Xbox Live match and there's no community anymore.
